SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

Current Report

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

April 4, 2016

Date of Report (Date of earliest event reported)

Endurance Specialty Holdings Ltd.

(Exact name of registrant as specified in its charter)

Waterloo House, 100 Pitts Bay Road, Pembroke HM 08, Bermuda

(Address of principal executive offices, including zip code)

(441) 278-0400

(Registrant’s telephone number, including area code)

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Item 7.01. Regulation FD Disclosure.

Attached hereto as Exhibit 99.1 are the 2015 Loss Development Triangles of Endurance Specialty Holdings Ltd. (the “Company”), which provide greater detail on the Company’s reserves for losses and loss adjustment expenses. The 2015 Loss Development Triangles include loss development triangles for net paid and reported loss and loss adjustment expenses by accident year at annual evaluation dates, with the most recent evaluation being as of December 31, 2015. In addition, the 2015 Loss Development Triangles include accident year summary exhibits containing gross, ceded and net results by segment and business line as of December 31, 2015. A copy of this document is available in the Investor Relations section of the Company’s website at www.endurance.bm.

The information in Item 7.01 of this report, including the Exhibit 99.1 furnished pursuant to Item 7.01 of this report, is being furnished, not filed, pursuant to Regulation FD. Accordingly, the information in Item 7.01 of this report will not be incorporated by reference into any registration statement filed by the Company under the Securities Act of 1933, as amended, unless specifically identified therein as being incorporated therein by reference. The furnishing of the information in this report is not intended to, and does not, constitute a determination or admission by the Company that the information in this report is material or complete, or that investors should consider this information before making an investment decision with respect to any security of the Company or any of its affiliates.

Safe Harbor for Forward-Looking Statements

Some of the statements in Exhibit 99.1 may include forward-looking statements which reflect our current views with respect to future events and financial performance. Such statements may include forward-looking statements both with respect to us in general and the insurance and reinsurance sectors specifically, both as to underwriting and investment matters. Statements which include the words “expect,” “intend,” “plan,” “believe,” “project,” “anticipate,” “seek,” “will,” and similar statements of a future or forward looking nature identify forward-looking statements in Exhibit 99.1 for purposes of the U.S. federal securities laws or otherwise. We intend these forward-looking statements to be covered by the safe harbor provisions for forward-looking statements in the Private Securities Litigation Reform Act of 1995.

All forward-looking statements address matters that involve risks and uncertainties. Accordingly, there are or may be important factors that could cause actual results to differ from those indicated in the forward-looking statements. These factors include, but are not limited to, (i) changes in the size of the claims payable by the Company relating to natural catastrophes, (ii) greater frequency or severity of claims and loss activity than the Company’s underwriting, reserving or investment practices anticipate based upon historical experience or industry data, (iii) trends in rates for property and casualty insurance and reinsurance, (iv) changes in the judicial, legislative or regulatory environments in which the Company operates, (v) changes in general economic conditions, including foreign currency exchange rates, inflation and other factors and (vi) the other factors described in our most recent Annual Report on Form 10-K and Quarterly Reports on Form 10-Q filed with the U.S. Securities and Exchange Commission.

Forward-looking statements speak only as of the date on which they are made, and we undertake no obligation publicly to update or revise any forward-looking statement, whether as a result of new information, future developments or otherwise.

Item 9.01. Financial Statements and Exhibits

The following exhibit is furnished as part of this report:

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

Dated: April 4, 2016

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